A Stable Li Metal Anode with Electrochemically Treated Poly(ethylene oxide) Coating for Lithium Oxygen Batteries

Abstract

Rechargeable lithium-oxygen batteries (LOBs) has being considered as one of the most promising candidates for the next-generation high energy-density batteries. The long-term cycling ability of LOBs is closely related to the stability of Li metal anode in an oxygen-rich environment. In this study, a polymer-supported solid electrolyte interphase (PS-SEI) layer generated on Li metal surface was investigated to minimize side reactions between Li metal anode and electrolyte as well as highly reactive oxygen moieties and soluble catalysts (redox mediators, RMs). The improved robustness of the PS-SEI layer can be attributed to uniformly-distributed stiff oxygen-containing components interacted with flexible ionic conductive polymer matrix. In addition, the impedance spectra of the LOBs with a PS-SEI before and after the cycling revealed a stabilized interface between Li anode and the electrolyte. The PS-SEI incresed the cycle life of LOBs by more than 50% compared to the LOBs without PS-SEI under the same testing condition of 1.0 mAh cm-2 at 0.2 mA cm-2. The combination of this protection layer and and an effective redox mediater such as (2,2,6,6-tetramethylpiperidin-1-yl) oxidanyl (TEMPO) further improved the performance of LOBs.